A. Field of the Invention
The invention relates to the production of acrylonitrile from propionitrile.
B. The Prior Art
A long standing problem in the manufacturing of adiponitrile from acrylonitrile has been the loss of adiponitrile by way of conversion to the by-product propionitrile, which, in a typical electrohydrodimerization reaction, occurs at a rate of about 4-7 mole % of the acrylonitrile employed as a starting material.
One attempt made to reconvert propionitrile to acrylonitrile involved a low temperature gas phase catalytic dehydrogenation in the presence of stannous oxide. According to U.S. Pat. No. 3,520,915, one-pass propionitrile conversions of 15-25%, with selectivities to acrylonitrile of 80-90%, are attained at temperatures of 500.degree.-600.degree. C. with unspecified but comparable yields theorized at 300.degree.-700.degree. C. Conversion rates of this order of magnitude are obviously suitable for commercial application only where a series of repeat passes can be employed.
A dehydrogenation reaction for propionitrile in which high acrylonitrile selectivity is maintained in conjunction with a commercially acceptable propionitrile conversion would be a significant advance in the art and is an object of this invention.